fix [#29735] Blender crashes with ACCESS_VIOLATION when snapping cursor to camera

1 files changed, 6 insertions, 7 deletions

diff --git a/source/blender/editors/space_view3d/view3d_snap.c b/source/blender/editors/space_view3d/view3d_snap.c
index a2173537c8c..ac1c71cd344 100644
--- a/source/blender/editors/space_view3d/view3d_snap.c
+++ b/source/blender/editors/space_view3d/view3d_snap.c
@@ -758,16 +758,17 @@ void VIEW3D_OT_snap_cursor_to_grid(wmOperatorType *ot)
 static void bundle_midpoint(Scene *scene, Object *ob, float vec[3])
 {
 	MovieClip *clip= object_get_movieclip(scene, ob, 0);
-	MovieTracking *tracking= &clip->tracking;
-	MovieTrackingObject *object= tracking->objects.first;
+	MovieTracking *tracking;
+	MovieTrackingObject *object;
 	int ok= 0;
-	float min[3], max[3], mat[4][4], pos[3], cammat[4][4];
+	float min[3], max[3], mat[4][4], pos[3], cammat[4][4] = MAT4_UNITY;
 
 	if(!clip)
 		return;
 
-	unit_m4(cammat);
+	tracking= &clip->tracking;
 
+	/* XXX - seems like an unneeded side effect, snapping should _not_ set the active camera for eg. - campbell */
 	if(!scene->camera)
 		scene->camera= scene_find_camera(scene);
 
@@ -778,7 +779,7 @@ static void bundle_midpoint(Scene *scene, Object *ob, float vec[3])
 
 	INIT_MINMAX(min, max);
 
-	while(object) {
+	for (object= tracking->objects.first; object; object= object->next) {
 		ListBase *tracksbase= BKE_tracking_object_tracks(tracking, object);
 		MovieTrackingTrack *track= tracksbase->first;
 		float obmat[4][4];
@@ -804,8 +805,6 @@ static void bundle_midpoint(Scene *scene, Object *ob, float vec[3])
 
 			track= track->next;
 		}
-
-		object= object->next;
 	}
 
 	if(ok) {